1. Field of the Invention
The present invention relates to a voltage generator for X-ray machines and an X-ray machine which uses such a voltage generator.
2. Description of the Prior Art
As is known, an X-ray machine is an apparatus able to produce and emit an X-ray beam, namely a radiation having a wavelength of between about 0.1 and about 10 nm.
An X-ray machine typically comprises an X-ray tube for producing the X-ray beam and a generator for energizing the X-ray tube. The X-ray tube and the generator may be located inside separate metal containers connected by electric wires which allow the generator to energize the X-ray tube. Alternatively, the X-ray tube and the generator may be located inside a single metal container. In this case, reference is made to X-ray machines with a “single-piece” structure.
Typically, X-ray machines are used to perform non-invasive diagnoses (radiography, radioscopy, scintigraphy, etc.) of objects which comprise inside them a first portion made of a material which absorbs the X-rays and a second portion made of material through which the X-rays are able to pass. For example, in the medical field, the material which absorbs the X-rays may consist of the dense tissues of the human body (typically, bones or teeth) and the material through which the X-rays can pass may consist of the soft tissues of the human body.
In the industrial sector, X-rays machines may be used to carry out checks as to any flaws in a solid metal body (for example, a pipe or an engine block).
For this purpose, an X-ray beam is directed onto the body on which the check is to be performed. The beam part which strikes the first portion is absorbed, while the beam part which strikes the second portion passes through the body. The X-ray beam, upon leaving the body, therefore has a force distribution which substantially reproduces the internal structure of the body.
The X-ray beam leaving the body is then detected so as to create a visible image of the internal structure of the body. The detection may be performed, for example, by directing the beam leaving the body onto a photographic plate which is sensitive to X-rays or onto a screen treated with rare earths. Alternatively, the image may be acquired digitally by directing the beam leaving the body onto an array of semiconductor photosensors.
The digital acquisition of the images created by means of X-rays is currently of growing interest since it allows the images to be stored on a digital storage medium (floppy disk, hard disk, etc.). This advantageously allows the creation of very compact image files in which the images do not risk deteriorating with time, as instead occurs in the case of images recorded on a photographic plate.
The digital acquisition of images of objects analysed by means of X-ray machines requires X-rays beams emitted by particularly small focal spots with a particularly large amount of energy. This would require providing the X-ray machine with a generator able to produce a particularly high supply voltage, for example ranging between 20 kV and 450 kV.
However, the known generators able to produce such high voltages imply large dimensions. This results in an X-ray machine which is bulky, heavy and difficult to handle. Moreover, these generators are not suitable, on account of their size, for use in X-ray machines which have the abovementioned “single-piece” structure.
U.S. Pat. No. 5,060,253 discloses a high-voltage power supply wherein the second winding of the transformer, the capacitors, and the diodes of the rectifier and voltage-doubler circuits, are all disclosed in an enclosure made from two half-shells, whereas the primary winding and the magnetic circuit are disposed outside the enclosure.
U.S. Pat. No. 4,694,480 discloses a hand held x-ray source and an integral generator for exciting the tube.